Links

Images

Classifications

H01R4/00—Electrically-conductive connections between two or more conductive members in direct contact and means for effecting or maintaining such contact

H01R4/58—Electrically-conductive connections between two or more conductive members in direct contact and means for effecting or maintaining such contact characterised by the form or material of the contacting members

H01R4/64—Connections between or with conductive parts having primarily a non-electric function, e.g. frame, casing, rail

H—ELECTRICITY

H01—BASIC ELECTRIC ELEMENTS

H01R—LINE CONNECTORS; CURRENT COLLECTORS

H01R13/00—Details of coupling devices of the kinds covered by groups H01R12/70 or H01R24/00-H01R33/00

H01R2201/26—Connectors or connections adapted for particular applications for vehicles

H—ELECTRICITY

H01—BASIC ELECTRIC ELEMENTS

H01R—LINE CONNECTORS; CURRENT COLLECTORS

H01R4/00—Electrically-conductive connections between two or more conductive members in direct contact and means for effecting or maintaining such contact

H01R4/02—Soldered or welded connections

H01R4/029—Welded connections

Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

Abstract

For the fastening or connecting of electrical conductors to a unit in a higher
position an attachment device with a sleeve-shaped contact piece (1) and a cap (9) is
proposed. The contact piece (1) is connected by positive material locking to the unit
in a higher position with the connecting region (2). The contact piece (1) at least near
the attachment face (6) comprises an external contour which corresponds to a polygon
in cross-section. The cap (9) at least partially closes the orifice (4) in the vicinity of
the connecting region (2).

Description

The invention relates to an attachment device with a contact piece which can be
connected on the face and with positive material locking to a unit in a higher position
and with a cap.

The invention serves as a fastening and connecting facility and is used in
particular in automobile construction as a point of attachment preferably for an earth
contact.

The necessity of earthing electrical systems, particularly in automobiles and the
like is sufficiently known. According to EP 0 641 944 A1 there is a facility for
securing an earth contact of this kind in that a weld stud with an outer thread is
fastened to a car body or another component and thus serves as a fastening and
connecting facility for an electrical conductor. The weld stud has a flange which
serves as contact face. The functionality of the contact face and the outer thread of the
weld stud must be guaranteed by the welding process and subsequent lacquering
procedures.

The welding process threatens the functionality of the attachment, as, in
particular in the arc welding process welding splashes arise. These can stick to the
thread and make tightening and loosening of a corresponding nut difficult. Further,
according to EP 0 487 365 B1 the fastening of an electrical attachment device by
means of resistance welding is known.

The welding process has to be carried out before the car body sheet is lacquered.
The lacquer at the connecting point between the attachment device and the car body
sheet prevents a well-formed weld seam and in this way reduces the lifespan of the
positive material locking connection.

For these reasons measures are taken which protect the outer thread and the
contact face on the weld stud from welding and lacquer splashes. A protective
measure of this kind consists of a flange nut being mounted on the weld stud before
the welding process. So that the whole outer thread is protected the flange nut is
preferably designed as a cap nut.

The flange nut is mounted on the contact face at high initial tension. If the initial
tension is too low there is a danger that, owing to the heat occurring during the
welding process, the connection between the nut and the weld stud becomes detached.
In subsequent lacquering procedures lacquer can accumulate between nut and weld
stud owing to capillary action. This can lead to the contact face being covered with an
insulating layer.

The weld stud offers a facility for fastening by means of a correspondingly
designed connection piece on the electrical conductor and the flange nut. Mounting
the electrical conductor can only take place from the direction in which the weld stud
extends. The outer thread on the weld stud must be of a certain length, so that secure
clamping of a cable by a nut is guaranteed. Owing to the resulting extension of the
weld stud out of the plane of the car body sheet, sufficient space must be provided on
the mounting side for fastening the earth contact.

The weld stud is preferably welded onto thin car body sheets by the stud
welding process. To fasten the electrical conductor, a sufficient torsion must be
generated when the flange nut is tightened, so that a secure electrical contact is
possible. Mounting the flange nut onto the welded-on weld stud can cause the
connection between weld stud and car body sheet to become detached or the car body
sheet to be bent, owing to the torsion required.

The object of the present invention is to make available an attachment device
which represents effective protection against contamination of the contact face and
additionally withstands a higher torsional stress.

This object is achieved according to the invention by a contact piece and a cap
with the features of claim 1. Advantageous configurations and further developments
are given in the dependent claims.

An attachment device has a contact piece, which is connectable on the face and
with positive material locking to a unit in a higher position, and a cap, wherein the
contact piece is designed as sleeve-shaped and the cap is arranged in such a way that
the cap at least partially closes an orifice of the contact piece in the vicinity of a
connecting region. "Arranged" in this context means that the cap is connected directly
or indirectly to the contact piece. The cap in this way prevents welding splashes
reaching the inside of the orifice. In subsequent lacquering procedures the cap
effectively prevents the penetration of lacquer particles into the inside of the orifice,
which can result in insulation of the contact face.

The sleeve-shaped design of the contact piece allows fastening of additional
attachment units on both sides. For this purpose the cap can be removed after the
lacquering procedures. The sleeve-shaped design of the contact piece in this way
allows two possibilities of access to the through aperture. With a corresponding
orifice in the car body sheet the earth contact can thus also be fitted from the side of
the car body sheet remote from the contact piece with the weld seam.

The sleeve-shaped configuration of the contact piece allows good heat
conduction during the welding process and leads to a lower thermal stress of the car
body sheet. The lower thermal stress allows larger external diameters of the contact
piece and thus a larger connecting region to be used. In this way the attachment
device withstands a higher torsional stress.

Owing to the sort of thermal load on the attachment device which arises during
positive material locking of this device to the higher unit, it is advantageous to
produce the cap from a heat-proof material. With a view to the area of application, in
particular the fastening of an earth cable, it makes sense to produce the cap from an
electrically non-conducting material, to allow controlled further conduction of
electrical charge. Additionally, in this way it is avoided that the arc develops towards
the cap during the welding process and damages it. For these reasons a cap of plastics
material is to be recommended, corresponding to an advantageous further
development.

After the cap has been fastened to the contact piece, the cap preferably projects
beyond the connecting region of the contact piece. In this way the cap can be used for
centring the attachment device during the welding process. Correspondingly designed
positioning aids on the car body sheet support self-centring. This is particularly
suitable for automated manufacture, as found in automobile construction.

If the possibility of fastening an earth contact on both sides can be dispensed
with, the contact piece can be designed as a sheath, according to another further
development. An embodiment of such a kind allows the fastening of an earth contact,
after removing the cap, only from the side of the car body sheet remote from the weld
seam. With this embodiment the attachment face for an earth contact is threatened by
contamination such as welding or lacquer splashes only from one side, owing to the
lack of a through aperture. The cap alone thus offers effective protection of the
attachment face.

For a secure welding process in automated manufacture structural restrictions
have to be taken into consideration. For example, it must be guaranteed that the
contact piece is always taken up by the welding robot in a defined orientation. This
ensures that the contact piece is connected to the metal sheet with its connecting
region. For this purpose the contact piece comprises a reduced cross-section opposed
to the connecting region in the vicinity of the attachment face compared with other
regions. This reduced cross-section ensures that the contact piece can be taken up by
the welding device at a pre-determined orientation.

The contact piece with its orifice offers the facility of fastening an earth contact.
It is particularly advantageous, according to an advantageous further development,
that at least a partial region of the outer face of a channel adjoining the orifice is
designed as an inner thread. The inner thread in conjunction with a corresponding
screw represents a detachable and secure fastening of the earth contact. With a
correspondingly designed cable lug on the earth cable the cable can be clamped to the
metal attachment face of the contact piece with the screw. In this way a relatively
large area which is particularly suitable for the further conduction of electrical charge
is made available.

According to yet another advantageous further development the object of the
invention is characterised in that the contact piece at least near the attachment face has
an outer contour which corresponds to a polygon in cross-section. This specially
designed cross-section in conjunction with a correspondingly designed cable lug
represents an anti-rotation unit which prevents rotation of the electrical conductor
during fastening with a screw. Rotation of the electrical conductor round the contact
piece can result in the electrical conductor becoming detached from other fastening
points. A rotation of this kind can be prevented in that the cable lug has raised areas,
the arrangement of which is adapted to the polygonal cross-section of the contact
piece. In this way positive locking is achieved between cable lug and contact piece.

According to yet another advantageous further development it is proposed that
the contact piece at least near the connecting region comprises a welded edge. The
welded edge is to be designed in such a way that it is suitable for the welding process
used for fastening the contact piece on the car body sheet.

According to yet another advantageous embodiment of the invention it is
proposed that the cap is fastened to the contact piece from inside. In this way no
additional faces have to be provided on the contact piece to be placed onto the metal
sheet during the welding process. A further advantage is that the fastening of the cap
on the contact piece is protected against external environmental influences owing to
the surrounding outer face.

The connection between cap and contact piece is preferably designed as
detachable. This embodiment facilitates the fastening of the earth contact from the
side of the metal sheet remote from the weld seam. The detachable connection is
preferably to be designed as a snap connection.

Corresponding to an advantageous further development the snap connection is
designed in such a way that the contact piece on the outer face of the orifice
comprises a groove and the cap has a corresponding collar, the collar of the cap
engaging in the groove. The groove and the collar are preferably to be designed as
peripheral. If a collar designed in such a way is located in a peripheral groove and in
this way differently orientated contact faces arise between contact piece and cap, this
snap connection acts similarly to a labyrinth seal. This embodiment of the snap
connection thus represents an effective protection against lacquer splashes. As collar
and groove are designed as peripheral, during joining only the axial orientation of
contact piece and cap is significant.

According to yet another advantageous further development the object of the
invention is characterised in that the attachment device comprises a stud which is
connected to the contact piece. The stud has two end regions, wherein one end region
projects beyond the attachment face of the contact piece and the other end region is
connected to the cap. The end of the stud which is connected to the cap is preferably
designed in such a way that the cap can be fastened on the outer face of the stud. The
end region of the stud which projects beyond the attachment face of the contact piece
is preferably designed in such a way that it closes the orifice of the contact piece near
the attachment face and comprises a flange which serves to fasten the electrical
conductor on the attachment face of the contact piece.

According to yet another configuration it is proposed that the cap fastened to the
stud contacts the contact face in such a way that it at least partially closes the orifice
near the connecting region. Preferably the cap comprises raised areas on the side
remote from the stud, which contact the outer face of the channel of the contact piece.
Preferably this raised area is designed as a peripheral collar.

According to yet another configuration it is proposed that the stud has a head,
which is adjacent to the attachment face, on the end which protrudes beyond the
attachment face. The stud is connected to the contact piece before the lacquering
procedures in such a way that the head of the stud is located on the attachment face of
the contact piece. In this way electrically insulating lacquer splashes are prevented
from reaching the attachment face. To fasten the electrical conductor after the
lacquering process the stud is detached.

Further details and advantages of the device according to the invention are
explained with reference to the embodiments illustrated in the drawings.

Fig. 1 shows a sleeve-shaped embodiment of the contact piece in cross-section
with a rotationally symmetrical plastics material cap, snap connection and screw.

Fig. 2 shows a view from below of the contact piece designed as sleeve-shaped.

Fig. 3 shows a further sleeve-shaped embodiment of the contact piece with
plastics material cap and screw.

Fig. 4 shows an illustration of an embodiment in assembled state on a metal
sheet.

The contact piece 1 of the attachment device is connected on the face and with
positive material locking on and with the connecting region 2 to a higher unit. The
higher unit preferably represents a car body sheet to which a cable is to be fastened.
The positive material locking is produced according to the arc-stud welding process.

The contact piece 1 is designed as sleeve-shaped. Opposed to the connecting
region 2, the contact piece 1 comprises an attachment face 6. The attachment face 6
allows the fastening of an electrical conductor which ensures controlled further
conduction of electrical charge. Fastening of the electrical conductor takes place in
this embodiment by clamping an electrical conductor. The clamping preferably takes
place detachably. For this reason the contact piece 1 in the vicinity of the attachment
face 6 has an inner thread 8 which is designed on the outer face of a channel 7.
Fastening of the electrical conductor takes place with a stud 11, which is preferably
designed as a screw.

The contact piece 1 at least near the attachment face 6 comprises an external
contour 3 which corresponds to a polygon in cross-section, as Fig. 2 shows. The
embodiment illustrated has an octagonal cross-section. This special cross-section with
corresponding devices on the electrical conductor forms an anti-rotation unit which
prevents rotation of the electrical conductor when the screw is tightened. For this
purpose cable lug and contact piece 1 enter into a positive locking connection.
Corresponding to the number of side faces of the polygon of the external contour 3
and the number of positive locking raised areas on the cable lug, there are various
possibilities for the orientation of the electrical conductor during fastening thereof.

Owing to the preferred area of application of this attachment device in
automobile construction, design of the external geometry is to be undertaken with
automated manufacture in mind. For this reason the contact piece 1 has a reduced
cross-section in the vicinity of the attachment face 6 compared with other regions.
This reduced cross-section is designed as circular and allows controlled taking up and
fixing of the contact piece 1 by a welding robot which undertakes the positive
material locking connection to the unit in a higher position. Additionally, the cap 9 of
the attachment device is designed in such a way that, after being fastened to the
contact piece 1, it projects beyond the connecting region 2. With corresponding
positioning aids, here a positioning aperture, on the car body sheet, self-centring takes
place by means of the cap 9 during fastening of the contact piece 1.

For a secure fastening process of the contact piece 1 to a metal sheet, a
correspondingly designed connecting region 2 is to be provided, which is suitable for
the arc welding process. The embodiment illustrated allows this in that the fastening
of the cap 9 to the contact piece 1 is fitted inside the contact piece 1. The fastening of
the cap 9 on the contact piece is preferably to be designed as detachable, to allow
fixing of the electrical conductor on both sides.

The embodiment illustrated is characterised in that the connection of the cap 9
to the contact piece 1 is designed as a snap connection. The advantages of a snap
connection are the relatively simple geometry which the elements to be connected
need to comprise and the small amount of time required to produce or detach this
connection.

The contact piece 1 of the embodiment illustrated comprises for this purpose a
groove 5 in the outer face of the channel 7. The groove in this embodiment is
peripheral and designed as orientated radially outwards. The cap 9 has a
corresponding collar 10, which in this embodiment is also designed as peripheral. The
snap connection arises in that the collar 10 of the cap 9 engages in the groove 5 of the
contact piece 1. The combination of the peripheral groove 5 and the corresponding
collar 10 in the joined state has the advantage that the snap connection represents an
effective protection against lacquer splashes.

The contact piece 1 is assembled with the cap 9 and the stud 11 and then
fastened to the bodywork as a structural unit by the arc-stud welding process.

Fig. 3 shows a further embodiment of the attachment device with a cap and a
stud. The contact piece 1 is designed as sleeve-shaped and connectable on the face to
a unit in a higher position, not illustrated. The contact piece 1 comprises a connecting
region 2. An attachment face 6 is designed opposed to the connecting region 2. A
cross-section near the attachment face 6 is reduced compared to other regions. The
contact piece 1 has an inner thread 8. Near the attachment face 6 the contact piece 1
has an external contour 3 which corresponds to a polygon in cross-section. Near the
connecting region 2 the contact piece 1 is designed with a welded edge 12.

The device according to Fig. 3 comprises a stud 11 which is connected to the
contact piece 1. The stud in this embodiment is designed as a screw. The screw is
connected to the contact piece 1 via the inner thread 8. The screw comprises two end
regions. One end region projects beyond the attachment face 6 of the contact piece 1
and is designed as a screw head. The screw head locks with the attachment face 6 and
thus protects the attachment face 6 from welding and lacquer splashes. The other end
region of the screw protrudes beyond the inner thread 8.

An orifice 4 of the contact piece 1 in the vicinity of the connecting region 2 is at
least partially closed with a cap 9. The cap 9, made of plastics material, projects in the
assembled state beyond the connecting region 2. The cap 9 is fastened on the open
end region of the screw, which projects beyond the inner thread 8. The cap 9
comprises a flexible collar 10. This collar 10 contacts the outer face of the channel 7
peripherally. In this way the inner thread 8 is protected against environmental
influences.

Fig. 4 shows the embodiment according to Fig. 3 in the assembled state. The
contact piece 1, the stud 11 and the cap 9 form a structural unit. This is fastened to a
metal sheet 15 by the arc-stud welding process. The weld seam is denoted by 14. A
cable lug 13 of an electrical conductor is fastened to the contact piece 1 with the stud
11, which in this embodiment is represented as a screw. The stud 11 is detached from
the contact piece 1 while the cable lug 13 is fastened. If the mounting of the cable lug
13 requires removal of the stud 11, the cap 9 is also detached from the attachment
device. After renewed mounting of the stud 11 the cap 9 is connected to the stud 11
again and thus protects the inner thread 8 from environmental influences.

Claims (14)

Attachment device with a contact piece (1) which is connectable on the face
and with positive material locking to a unit in a higher position and with a cap (9)
which is connected to the contact piece (1), characterised in that the contact piece (1)
is designed as sleeve-shaped and the cap (9) is arranged in such a way that the cap (9)
at least partially closes an orifice (4) of the contact piece (1) in the vicinity of a
connecting region (2).

Device according to claim 1, characterised in that the cap (9) consists of a
heat-resistant and electrically non-conducting material, preferably a plastics material.

Device according to claim 1 or 2, characterised in that the cap (9) projects
beyond the connecting region (2).

Device according to one of claims 1 to 3, characterised in that the contact
piece (1) is designed as a sheath.

Device according to one of claims 1 to 4, characterised in that the contact
piece (1) comprises an attachment face (6) designed as opposed to the connecting
region (2), wherein the contact piece (1) has a reduced cross-section in the vicinity of
the attachment face (6) compared with other regions.

Device according to one of claims 1 to 5, characterised in that the contact
piece (1) has an inner thread (8).

Device according to one of claims 1 to 6, characterised in that the contact
piece (1) at least near the attachment face (6) has an external contour (3) which
corresponds to a polygon in cross-section.

Device according to one of claims 1 to 7, characterised in that the contact
piece (1) at least near the connecting region (2) has a welded edge (12).

Device according to one of claims 1 to 8, characterised in that the cap (9) is
fastened to the contact piece (1) from inside.

Device according to claim 9, characterised in that the cap (9) is detachably
connected to the contact piece (1).

Device according to claim 10, characterised in that the detachable connection
is designed as a snap connection.

Device according to claim 11, characterised in that the contact piece (1) on the
outer face of a channel (7) comprises a groove (5) and the cap (9) has a corresponding
collar (10), the collar engaging in the groove (5).

Device according to one of claims 1 to 8, characterised in that the device
comprises a stud (11) which is connected to the contact piece (1) and has two end
regions, wherein one end region projects beyond the attachment face (6) and the other
end region is connected to the cap (9).

Device according to claim 13, characterised in that the stud has a head (16)
which is adjacent to the attachment face (6).

Ground wire connecting device for use in motor vehicle, has lug attached to body part, and screw or nut attached to retaining unit that is connected with body part in fixed manner on side opposite to connecting lug